U.S. patent number 4,285,467 [Application Number 06/053,675] was granted by the patent office on 1981-08-25 for three-port thermally responsive valve.
This patent grant is currently assigned to Eaton Corporation. Invention is credited to Edgar W. Maltby.
United States Patent |
4,285,467 |
Maltby |
August 25, 1981 |
Three-port thermally responsive valve
Abstract
A three-port thermally responsive valve for alternately valving
an intermediate fluid port with adjacent upper and lower fluid
ports. A single valve member is movably contained within a housing
fluid passageway and spring-biased in a first position so that a
sealing surface at each end of the valve member is respectively
engageable with and spaced from corresponding valve sealing
surfaces in the fluid passageway. The sealing surfaces on the valve
member are spaced with respect to the valve sealing surfaces in the
housing fluid passageway to maintain isolation of the upper and
lower fluid ports until valving of the intermediate fluid port with
either the upper or lower fluid port is completed. When
predetermined temperatures are encountered, a thermally responsive
actuator connected to the valve member by a rod overcomes the
biasing force generated by the spring and moves the valve member to
the second valved position.
Inventors: |
Maltby; Edgar W. (Elgin,
IL) |
Assignee: |
Eaton Corporation (Cleveland,
OH)
|
Family
ID: |
26732125 |
Appl.
No.: |
06/053,675 |
Filed: |
July 2, 1979 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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841422 |
Oct 12, 1977 |
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Current U.S.
Class: |
236/86; 236/101A;
236/100 |
Current CPC
Class: |
F16K
31/002 (20130101); F02M 31/083 (20130101); G05D
23/185 (20130101); Y02T 10/12 (20130101); Y02T
10/126 (20130101) |
Current International
Class: |
F02M
31/02 (20060101); F16K 31/00 (20060101); F02M
31/083 (20060101); G05D 23/185 (20060101); G05D
023/12 () |
Field of
Search: |
;236/86,87,11C,100,11A,99K ;137/846,625.27 ;123/117A |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Tapolcai, Jr.; William E.
Attorney, Agent or Firm: McCloskey; R. J. Johnston; R.
A.
Parent Case Text
This is a continuation of application Ser. No. 841,422, filed Oct.
12, 1977, now abandoned.
Claims
What is claimed is:
1. A thermally responsive device for valving a plurality of fluid
ports, comprising:
(a) a housing means, said housing means defining
(i) a fluid chamber,
(ii) first, second and third spaced fluid ports communicating with
said fluid chamber,
(iii) a transversely extending stop surface intermediate said first
and second fluid ports;
(iv) a first valve sealing surface integrally formed by said
housing means;
(v) a second valve sealing surface integrally formed by said
housing means and spaced from said first valve sealing surface;
(b) valve means disposed within said fluid chamber, said valve
means including a valve member movable between a first valving
position, an intermediate position, and a second valving position,
and having first and second spaced seal means thereon, said valve
member further including a flanged portion adjacent said first seal
means, said flanged portion being engageable with said stop
surface, in said first position said first seal means seals against
said first valve sealing surface for isolating said first and
second fluid ports from each other, said second seal means is
spaced from said second valve sealing surface for fluidly
communicating said second fluid port with said third fluid port,
said flanged portion being in abutment with said stop surface, in
said intermediate position said first seal means remains sealed
against said first valve sealing surface and said second seal means
against said second seal surface for isolating said first fluid
port from said second and third fluid ports, and in said second
valving position said first seal means is spaced from said first
valve sealing surface for fluidly communicating said first fluid
port with said second fluid port and said second seal means remains
sealed against said second valve sealing surface for isolating said
second fluid port from said third fluid port; said flanged portion
being spaced from said stop surface in said intermediate and said
second positions;
(c) means biasing said valve member to said first position such
that said flanged portion abuts said stop surface; and,
(d) thermally responsive means associated with said housing means
and including means operative to move said valve member between
said first and second positions in response to predetermined
temperatures.
2. The device as defined in claim 1, wherein,
(a) said first valve sealing surface is located intermediate said
first and second fluid ports; and
(b) said second valve sealing surface is located intermediate said
second and third fluid ports.
3. The device as defined in claim 1, wherein said first and second
seal means are formed from an elastomeric material.
4. The device as defined in claim 1, wherein said housing means
includes a lower housing member having said first and second fluid
ports spaced thereon, and an upper housing member having said third
fluid port located thereon, said upper and lower housing members
being joined in a fluid sealing arrangement along a parting
line.
5. The device as defined in claim 1, wherein said upper and lower
housing members are formed from a plastic material.
6. The device as defined in claim 1, wherein said upper and lower
housing members are sonically welded together at said parting
line.
7. The device as defined in claim 1, wherein said first, second and
third fluid ports are disposed in a common alignment.
8. The device as defined in claim 1, further comprising a check
valve means disposed within said fluid chamber intermediate said
valve member and said third fluid port for preventing fluid flow in
a direction from said third fluid port to said second fluid port
and permitting fluid flow in a direction from said second fluid
port to said third fluid port.
9. The device as defined in claim 8, wherein said check valve means
includes a resilient tubular member having one end converging and
terminating in a pair of flaps, said flaps having opposed surfaces
normally in fluid sealing contact with each other, said flaps
opening in response to a pressure differential in only one
direction to permit fluid flow through said tubular member.
10. A thermally responsive device for valving a plurality of fluid
ports, comprising:
(a) housing means, said housing means defining
(i) a fluid chamber,
(ii) first, second and third spaced fluid ports communicating with
said fluid chamber,
(iii) a lower housing member having said first and second fluid
ports spaced thereon,
(iv) an upper housing member having said third fluid port located
thereon,
(v) a first valve sealing surface integrally formed by said lower
housing member;
(vi) a second valve sealing surface integrally formed by said upper
housing member;
(vii) said upper and lower housing members being joined in a fluid
sealing arrangement along a parting surface located adjacent said
second valve sealing surface;
(b) valve means disposed within said fluid chamber, said valve
means including a valve member disposed within said fluid chamber,
said valve member being movable between a first valving position,
an intermediate position, and a second valving position, and having
first and second spaced seal means thereon, in said first position
said first seal means seals against said first valve sealing
surface for isolating said first and second fluid ports from each
other, said second seal means is spaced from said second valve
sealing surface for fluidly communicating said second fluid port
with said third fluid port, in said intermediate position said
first seal means remains sealed against said first valve sealing
surface and said second seal means seals against said second seal
surface for isolating said first fluid port from said second and
third fluid poets, and in said second valving position said first
seal means is spaced from said first valve sealing surface for
fluidly communicating said first fluid port with said second fluid
port and said second seal means remains sealed against said second
valve sealing surface for isolating said second fluid port from
said third fluid port;
(c) means biasing said valve member to said first position; and
(d) thermally responsive means associated with said housing means
and including means operative to move said valve member between
said first and second positions in response to predetermined
temperature.
11. The device as defined in claim 10, wherein said upper and lower
housing members are formed from a plastic material.
12. The device as defined in claim 10, wherein said upper and lower
housing members are sonically welded together at said parting
line.
13. The device as defined in claim 10, wherein said first, second
and third fluid ports are disposed in a common alignment.
14. The device as defined in claim 10, further comprising a check
valve means disposed within said fluid chamber intermediate said
valve member and said third fluid port for preventing fluid flow in
a direction from said third fluid port to said second fluid port
and permitting fluid flow in a direction from said second fluid
port to said third fluid port.
15. The device as defined in claim 14, wherein said check valve
means includes a resilient tubular member having one end converging
and terminating in a pair of flaps, said flaps having opposed
surfaces normally in fluid sealing contact with each other, said
flaps opening in response to a pressure differential in only one
direction to permit fluid flow through said tubular member.
16. A thermally responsive device for valving a plurality of fluid
ports, comprising:
(a) housing means, said housing means defining
(i) a fluid chamber,
(ii) first, second and third spaced fluid ports communicating with
said fluid chamber,
(iii) a lower housing member having said first and second fluid
ports spaced thereon,
(iv) an upper housing member having said third fluid port located
thereon,
(v) a first valve sealing surface integrally formed by said lower
housing member;
(vi) a second valve sealing surface integrally formed by said upper
housing member;
(vii) said upper and lower housing members being joined in a fluid
sealing arrangement along a parting surface located adjacent said
second valve sealing surface;
(b) valve means disposed within said fluid chamber, said valve
means including a valve member disposed within said fluid chamber,
said valve member being movable between a first valving position,
an intermediate position, and a second valving position, and having
first and second spaced seal means thereon, in said first position
said first seal means seals against said first valve sealing
surface for isolating said first and second fluid ports from each
other, said second seal means is spaced from said second valve
sealing surface for fluidly communicating said second fluid port
with said third fluid port, in said intermediate position said
first seal means remains sealed against said first valve sealing
surface and said second seal means seals against said second seal
surface for isolating said first fluid port from said second and
third fluid ports, and in said second valving position said first
seal means is spaced from said first valve sealing surface for
fluidly communicating said first fluid port with said second fluid
port and said second seal means remains sealed against said second
valve sealing surface for isolating said second fluid port from
said third fluid port;
(c) means biasing said valve member to said first position;
(d) thermally responsive means associated with said housing means
and including means operative to move said valve member between
said first and second positions in response to predetermined
temperature; and
(e) check valve means disposed within said fluid chamber
intermediate said valve member and said third fluid port for
preventing fluid flow in a direction from said third fluid port to
said second fluid port and permitting fluid blow in a direction
from said fluid port to said third fluid port.
17. The device as defined in claim 16, wherein said check valve
means includes a resilient tubular member having one end converging
and terminating in a pair of flaps, said flaps having opposed
surfaces normally in fluid sealing contact with each other, said
flaps opening in response to a pressure differential in only one
direction to permit fluid flow through said tubular member.
Description
BACKGROUND OF THE INVENTION
Engine performance immediately after start-up can be improved by
diverting exhaust gases from the exhaust manifold to an area around
the carburetor for heating the intake air, thus permitting improved
vaporization of the fuel-air mixture. It has been a common practice
to utilize a three-port valve for valving an intake manifold vacuum
source to a vacuum motor which opens a heat valve enabling exhaust
gas heat to be transferred to the carburetor. As the engine
continues to operate, the exhaust gas temperature approaches a
level which can result in excessive heating of the incoming air to
the carburetor leading to vapor lock. Before this point is reached,
the three-way valve shuts off the vacuum motor by isolating the
vacuum source and valving the motor to a venting port. Prior art
devices in common use for performing these valving functions
include the standard three-port spring biased ball-type valve.
Valve chatter is a problem encountered with ball-type three port
valves. During valving of the vacuum motor port between the vacuum
source and the venting source, there is a point at which the vacuum
source is fluidly connected to the venting port resulting in a
sudden pressure build-up around the valve ball which tends to lift
the ball off its seat until overcome by the return spring. As the
spring returns to its normal position, the fluid pressure again
lifts the ball off its seat setting up the chattering effect until
the ball seals off the vacuum source. A further problem associated
with the use of a standard three-port valve is that it has been
necessary to utilize an independently mounted check valve located
between the vacuum port of the three-way valve and the vacuum
source in order to isolate the vacuum motor from fluctuations in
the vacuum source caused by sudden vehicle accelerations. A
separately mounted check valve increases the total unit
manufacturing costs plus adds to installation costs.
SUMMARY OF THE INVENTION
In the present invention valve chatter encountered during operation
of a ball check type valve has been eliminated by utilizing a
unique arrangement of valve seal and sealing surface spacing which
permits the vacuum source to be isolated from the vacuum motor port
before venting. With the vacuum source isolated from the venting
port, the sudden flow of fluid from the venting port no longer
reacts against the valve member to overcome the action of the
retaining spring resulting in chatter of the valve member. This
sealing arrangement also permits a more precise valve action to
occur. Another advantage achieved by the present invention is that
a check valve member can be mounted directly within the valve body,
thus eliminating the need for a separate check valve mounted
exteriorly with respect to the three-port valve member, thus
providing a more compact assembly in which manufacturing and
installation costs are significantly reduced from previously
employed devices.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a plan view of the assembly of the device of the present
invention;
FIG. 2 is a cross-sectional view of a first embodiment of the
invention taken along section indicating lines 2--2 of FIG. 1 and
illustrates the valve in the first position wherein the thermal
element senses temperatures below a predetermined level;
FIG. 3 is a cross-sectional view similar to FIG. 2 illustrating the
valve in an intermediate position during which the valve member is
moving upward;
FIG. 4 is a cross-sectional view similar to FIG. 2 illustrating the
valve in the second position with the thermal element sensing
temperatures at or above a predetermined level;
FIG. 5 is a partial cross-sectional view of a second embodiment of
the invention similar to FIG. 2.
DETAILED DESCRIPTION
Referring to FIG. 1 and FIG. 2, a thermally responsive vacuum valve
indicated generally by numeral 10 is shown having a thermally
responsive actuator indicated generally by numeral 12 extending
from an adapter 14. A lower housing section 16 defining fluid
chamber portions 18 and 19 is provided which includes first and
second spaced fluid ports 20 and 22, preferably vertically aligned.
An upper housing section 24 defining a fluid chamber portion 26 is
provided and has formed therein a third fluid port 27 which is also
preferably aligned with ports 18 and 20. In the presently preferred
practice, upper housing 24 and lower housing 16 are preferably
injection molded from a suitable plastic material, such as a glass
filled nylon, and are joined together along a transverse parting
line to be hereinafter described, and sealed against fluid leakage
by any suitable means as, for example, a sonic welding process.
However, other materials and manufacturing techniques may be used
to fabricate and seal the housing sections without departing from
the present invention.
The adapter 14 has a tapered pipe thread 28 at one end and is
attached to the bottom end of lower housing section 16 which
permits assembly of the valve to the apparatus from which a medium
is to be sensed as, for example, on an engine for sensing the
temperature of the engine coolant. The housing sections are free to
rotate as a unit with respect to the adapter 14 thereby permitting
alignment of the fluid ports after installation to any desired
position.
A relatively thin wall tubular projection 30 is formed in the upper
end of the adapter 14 and has located and received therein the
lower end 32 of lower housing section 16. End 32 of lower housing
section 16 has a thickened cylindrical wall portion 34 with an
annular groove 36 formed therein in which is received a seal ring
38. Seal ring 38 provides a dynamic seal between the adapter 14 and
lower housing section 16. An upper portion 40 of tubular projection
30 has a wall thickness suitable for crimping. A tapered surface 42
is provided on lower housing section 16. Upper portion 40 is
crimped over surface 42 a sufficient amount to locate and retain
the lower housing in the adapter, but still allow relative rotation
therebetween at a breakaway torque from about 10 to 30 inch-pounds,
but preferably not exceeding 50 inch-pounds. The upper exterior
surface of adapter 14 is provided with a hexagonal pattern of
wrench flats, typically indicated by numeral 44, to facilitate
valve installation.
Referring now particularly to FIG. 2, a volumetrically thermally
responsive material 46 is provided which may be of any suitable
type well known in the art as, for example, a mixture of wax and
copper metallic flakes, is disposed within a retaining cup 48 which
is preferably formed from mild steel and attached to the lower
extremity of adapter 14. The mixture is enclosed in the cup by a
flexible cover in the form of a resilient, preferably elastomeric
diaphragm 50. A particularly suitable mixture of wax and copper
metallic flakes 46 is employed which has an abrupt volumetric
change across a predetermined narrow temperature band of
approximately 7 to 10 degrees Fahrenheit. The volume increase of
the mixture, while passing through this temperature range, is
sufficient to result in a movement of the retaining diaphragm 50 of
approximately 0.070-0.080 inch. Prior to and after passing through
this temperature band, the resultant linear expansion of the
mixture is only 0.0003 inch per .degree.F., an amount insufficient
to effect the performance of the valve. The wax and copper flake
mixture is preferably formulated to provide a volumetric increase
in excess of that initially required to actuate the valve in order
to compensate for subsequent deterioration of the wax over extended
periods of time and exposure to high temperatures which results in
reduced volumetric expansion.
A thin wall annular portion 52 formed on the bottom of adapter 14
is deformed over and around a flange provided on the periphery of
the retaining cup 48. The retaining cup 48 is preferably held in
place by crimping the thin wall portion 52 around the flanged end
of the retaining cup. The retaining diaphragm 50 is sealed against
the top surface 40 of the retaining cup and the end of the adapter,
thus confining the wax mixture 46 therein. The adapter 14 may be
fabricated from steel or other suitable material as, for example,
brass and has a centrally located bore 54 located therethrough and
a tapered counterbore 56 located at the thermal actuator, or lower,
end of the adapter. A plug 58 which conforms generally to the space
defined by the tapered counterbore 56 is received therein. A
disc-shaped spacer 60 having a top surface 61 is slidably received
in bore 54 and registers against the upper surface of plug 46. The
diaphragm 50, plug 58 and spacer 60 are all formed from a rubber
compound which is compatible with the wax-metal flake mixture and
suitable for service exposure to the temperatures encountered
during operating conditions. A rod 62, preferably fabricated from
aluminum, is located within bore 54 with the lower end thereof 64
in contact with spacer 60 and the other end 66 extending upwardly
into lower housing section 16. In operation, the expansion of the
mixture 32 is transferred through diaphragm 50, plug 58 and spacer
60 causing upward movement of rod 62. This function will be
described subsequently in greater detail.
Fluid ports 20 and 22 are formed in tubular projections 68 and 70
which are integrally molded with and extend from lower housing
section 16 such that ports 20 and 22 fluidly communicate with fluid
chamber portions 18 and 19, respectively. Similarly, fluid port 27
is formed in tubular projection 72 molded integrally with and
extending from upper housing section 24; and port 27 fluidly
communicates with fluid chamber portion 26. As best shown in FIG.
1, the three fluid ports 20, 22 and 27 are disposed in common
alignment along the upper and lower housing sections.
A transverse wall section 74 having an upper transverse surface 75
and a centrally located tubular portion 76 defining a bore 78
axially therethrough with rod 62 extending therethrough is located
within housing section 16 and intermediate fluid ports 20 and 22.
Bore 78 is also designated as a first valve sealing surface.
Clearance is provided between rod 62 and bore 78 sufficient for
permitting free fluid flow therethrough. A chamfer or tapered
surface 79 is provided along the upper edge of bore 78.
A registering counterbore 80 provided in the upper end of housing
section 16 has received and registered therein a diameter 82 formed
on and extending from the bottom end of the upper housing 24,
thereby locating housing section 24 with section 16. The junction
of the lower and upper housing sections forming parting line 83 is
later joined by a suitable technique, such as sonic welding.
A chamfered or tapered surface 84 is located intermediate third
fluid port 27 and second fluid port 22 and along the inner, lower,
edge of housing section 24. An annular groove 85 is provided
adjacent and located outward radially from tapered surface 84,
opening in an axial direction. Fluid chamber portion 26 defines a
bore 86 which is also designated as a second valve sealing
surface.
As shown in FIG. 2 an elongated, cylindrically shaped valve member
88 fabricated from a suitable material, preferably aluminum or
plastic, is located within the upper and lower housing sections. An
enlarged diameter portion 90 is formed near the end of the valve
member for locating and centering with respect to an internal
diameter 92 formed by fluid chamber portion 19. The radial
clearance between diameters 90 and 92 is sufficient to permit free
fluid flow therebetween. A lower transverse surface 94 on the valve
member 88 abuts with surface 75 of lower housing section 16, thus
limiting downward travel of the valve member. A lower end 95 of the
valve member is in contact with the upper end 66 of rod 62. Annular
grooves 96 and 98 are formed near the lower and upper ends of the
valve member, respectively. A seal ring 100 is contained in groove
96 while a seal ring 102 is contained in groove 98, and are
designated as first and second seal means, respectively. The upper
end of the valve member has a diameter 104 sized to clear internal
diameter 86 for permitting free fluid flow therebetween. In a
similar manner, the lower end of the valve member has a diameter
106 sized to clear bore 88 for allowing fluid flow therebetween
when seal ring 100 is spaced from tapered surface 79.
Tapered surfaces 79 and 84 permit seal rings 100 and 102 to engage
with bores 78 and 86, respectively, without damaging the seal
rings. The relative spacing of seal rings 100 and 102 with respect
to the spacing of tapered surfaces 79 and 84 will be subsequently
discussed in greater detail.
A biasing means in the form of a compression spring 110 preferably
wound from a chrome-silicon alloy steel is received over a diameter
108 of the valve member and guided thereon. The spring has one end
located in annular groove 85 with the other end thereof reacting
against a shoulder 112 near the lower end of the valve member for
maintaining the valve member in the first position.
Seal rings 38, 100 and 102 are preferably formed from an
elastomeric material capable of withstanding continuous exposure to
temperatures of 400.degree. to 500.degree. Fahrenheit without
degradation.
In operation, as shown in FIG. 2, valve member 88 is biased by
spring 110 to the first position, at sensed temperatures less than
a predetermined minimum. While in the first position, seal ring 100
is in sealing contact with bore 78 and seal ring 102 is spaced away
from bore 86. The gap between the tapered surface 84 and the seal
ring 102 allows fluid communication between the second fluid port
22 and third fluid port 27 through fluid chamber portions 26 and
19. In this first position, as shown in FIG. 2, the first fluid
port is sealed from the second fluid port by seal ring 100 in
sealing contact with bore 78.
It will be understood that rod 50 has a length that spans the
distance from the lower end 95 of valve member 88, while in the
first position (FIG. 2), to the top surface 61 of spacer 60 without
deflecting retaining diaphragm 36 or allowing excessive clearance
therebetween. While the valve member is in the above-described
first position, the thermally responsive actuator 12 is inactive
since the temperatures sensed are below those necessary to cause an
abrupt volumetric increase in the wax and metal flake mixture.
Referring now to FIG. 3, the valve member 88 is shown in an
intermediate position, between the first and second position,
wherein the thermally responsive actuator 12 is sensing a
temperature at the value which has resulted in a corresponding
abrupt volumetric increase of the wax and copper flake mixture 34.
Continued expansion of mixture 32 thereafter overcomes the biasing
force of spring 124 and moves rod 62 and valve member 88 upward
toward the second position. While valve member 88 is in this
intermediate position, the first seal ring 100 remains in sealing
engagement with bore 78 in lower housing section 16 and seal ring
102 has engaged with bore 86 in housing section 24. This dual
sealing feature permits the second fluid port 22 to be valved from
fluid communication with third fluid port 27 to fluid communication
with first fluid port 20 without fluid interaction between first
fluid port 20 and third fluid port 27. To achieve this result of
dual sealing, the spacing between seal rings 100 and 102 must
exceed the spacing between bores 78 and 86 so that seal ring 102
sealingly engages with tapered surface 84 and bore 86 before seal
ring 100 disengages with tapered surface 79. The effect of this
unique spacing arrangement is to eliminate chatter or vibration of
the valve member. In a typical application of the present device
the third fluid port is connected to a vacuum source on an engine
where it is then valved to the second fluid port, making the vacuum
source available to a plurality of engine control devices.
Heretofore, when the second fluid port required valving to the
first fluid port, after a venting port, fluid from the first port
would be drawn into the vacuum source, or third fluid port, which
tended to lift the valve member off the push rod until overcome by
the spring force.
As shown in FIG. 4, the valve member has completed its upward
motion and is in the second position with the thermally responsive
actuator 12 sensing temperatures above the value which results in
an abrupt volumetric increase of the wax and copper flake mixture
46. Valve member 88 has now moved upward by an amount sufficient to
space seal ring 100 away from tapered surface 79, permitting fluid
communication between fluid port 20 and fluid port 22 through fluid
chamber portion 18, bore 78, and fluid chamber portion 19. Seal
ring 102, already having sealed against the lower portion of bore
86, is now located further into bore 86 and continues to isolate
the third fluid port 27 from the first fluid port 22.
When sensed temperatures are again below the predetermined range,
the volume of the mixture 46 will contract permitting the spring
110 to return the valve member to the first position as shown in
FIG. 2. The operational sequence occurring during valve movement
from the second to the first position is then the reverse of that
described above.
There is shown in FIG. 5 a second embodiment of the invention which
is otherwise identical to the first embodiment but includes a check
valve member (shown generally by numeral 114) and preferably molded
from a resilient, high temperature resistant elastomeric material.
Upper housing member 116 defines counterbores 118 and 120 and a
shoulder 121 in which is received the check valve member 112. The
lower end of the check valve comprises a tubular portion 122 having
an outer diameter conforming to counterbore 116. A flange 124
having an outer diameter 126 that conforms to the diameter of
counterbore 120 is formed around the end of tubular portion 120. A
retaining disc 128 having a centrally located hole 130 and a
diameter 132 sized for a press fit with respect to counterbore is
pressed therein, thereby retaining the check valve member in place.
The retaining force generated by disc 128 serves to seal the flange
124 against shoulder 121 preventing fluid leakage around the
periphery of the check valve. The upper portion of the check valve
converges from a tubular configuration and terminates in a pair of
flaps 134 and 136 having the opposed surfaces thereof in sealing
contact. In operation, the check valve member permits fluid flow in
a direction from the flanged end to the flap end, since a positive
internal pressure differential across the flaps overcomes the
resilient tendency of the flaps to remain in sealing contact. Fluid
flow in the opposite direction is prevented since a positive
external pressure differential maintains the flaps in sealing
contact. By using the check valve member in combination with the
first embodiment of the invention, a constant vacuum supply can be
maintained on a vacuum motor (not shown) connected to fluid port 22
(FIG. 2), thus eliminating the need for a separate, individually
mounted check valve.
The present invention thus provides a device capable of receiving
different vacuum or pressure signals at two spaced ports and
alternately valving each to an intermediate fluid port in response
to predetermined temperatures by means of a single valve member and
a single thermally responsive actuator. The invention provides a
unique valving/isolating seal arrangement for valving between the
fluid ports while maintaining isolation of the fluid ports during
movement of the valve member.
Modifications and variations of the preferred forms of the
invention will be apparent to those having ordinary skill in the
art without departing from the teachings as hereinabove described,
and the invention is limited only by the following claims.
* * * * *